The possibility of a major accident is present in many maintenance and start-up activities in the industry. On Friday, October 2, 2015 four workers were treated for burns after an explosion and fire at a chemical plant along the Houston Ship Channel.
Although the direct cause of the explosion is still unknown, it is interesting to note that diluted silane mixtures with inert gases such as nitrogen or argon are even more likely to ignite when leaked into open air. Apparently, oxygen has an ignition suppressing nature. This fact is consistent with the remarkable experimental finding that the lower flammability limit of silane decreases continuously with successive dilution of air with an inert gas such as nitrogen. At the time of the explosion, silane was inadvertently released from a flange adjacent to a compressor while workers were in the process of inerting (using nitrogen).
Remember that plant maintenance and start-up activities are a significant cause of hazardous releases, and precautions should be taken to minimize risk during these activities. Specifically, it is critical to understand the nature of the hazard (e.g. even a 1% mixture of silane in pure nitrogen easily ignites when exposed to air).
For more practical advice and tools for improving the quality of maintenance activities please check out: Health and Safety Executive Guidance on Improving Maintenance and Reducing Human Error
For more information on the explosion please visit: News Article – Four Injured in Explosion at Plant in Pasadena